# Power electronics in electric utilities: static var compensators

Article Abstract:

There can be major, even damaging, amplitude variations in voltage transmitted over ac distribution lines because such systems are basically reactive networks. Thyristor-controlled static var generators (SVGs) can provide dynamic compensation through reactive generation and control. SVGs stay in sync with the lines' ac voltages and control transients, power oscillations, and voltage instabilities by use of thyristor-switched capacitors to generate the reactive power and thyristor-controlled reactors to absorb it. A SVG can be turned into a static var compensator (SVC) through the use of external control loops designed to control desired parameters of the ac power system. All solid-state SVCs are being developed using gate-turn-off thyristors. The SVC can increase the capacity of the power system through voltage support and increased stability margins.

Publication Name: Proceedings of the IEEE

Subject: Electronics

ISSN: 0018-9219

Year: 1988

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# The cascade EM algorithm

Article Abstract:

The cascade EM (CEM) algorithm is developed as an extension of the estimate-maximize (EM) algorithm that iteratively deduces maximum likelihood parameter estimates for incomplete sets of data. The CEM algorithm offers faster convergence to a solution with fewer computations per iteration by working with intermediate complete data specifications and performing intermediate EM steps at some iterations. The algorithm is successfully applied to a parameter identification problem for a continuous-time linear dynamic system with only discrete-time noisy observations. Details of the development of the algorithm and application to the example problem are described.

Publication Name: Proceedings of the IEEE

Subject: Electronics

ISSN: 0018-9219

Year: 1988

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# A Nonlinear Programming Approach to the Design of Cascade Compensators for Linear Control Systems

Article Abstract:

Cascade compensators improve the performance of single-loop linear control systems. A typical problem in designing a cascade compensator is discussed. It is formulated as a nonlinear programming problem. This formulation allows the design to be done by computer. A diagram of a standard-loop system with cascade compensation is included.

Publication Name: Proceedings of the IEEE

Subject: Electronics

ISSN: 0018-9219

Year: 1984

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